(CNN) -- Andres Iniesta could miss Spain's opening game at the World Cup after suffering a thigh injury in a warm-up match.
The Barcelona midfielder set up two goals for Spain in their emphatic 6-0 win over Poland in Murcia on Monday, but was substituted after just 39 minutes.
Iniesta missed a large chunk of Barcelona's season with a thigh complaint, but team doctors insisted the injury was only minor.
"We substituted him because he had some discomfort in the back part of the thigh," Spain's team doctor Dr Oscar Celada was quoted as saying by the UK Press Association.
"He didn't notice any tear and it has not got any worse. It was at the start of the match and as he wasn't comfortable, we made the change - it's a minor muscle injury.
"We will calmly carry out tests on Wednesday, but we can initially rule out any muscle tear. It's a minor injury, but we have to take precautions," he added.
Two of Spain's other injury doubts, Arsenal midfielder Cesc Fabregas and Liverpool striker Fernando Torres, both came on a substitutes against Poland -- and scored -- as they look to step up their fitness.
It was Torres' first action since playing for Liverpool against Portuguese side Benfica back in April.
"It was almost two months without playing since the Benfica game and I was really keen to come back," he said after the match.
"They have let me play for a while today and it was great to go out there and score."
As for Iniesta, it remains to be seen whether he will play any part in Spain's opening Group H game against Switzerland on June 16.